The Rev Dr Peter Mullen is a priest of the Church of England and former Rector of St Michael, Cornhill and St Sepulchre-without-Newgate in the City of London. He has written for many publications including the Wall Street Journal.

How mortal sins became 'lifestyle choices'

The controversy about the definition of marriage is just one part of a significant change in the development of public morality. For centuries European societies broadly accepted the Judaeo-Christian teaching about the nature of human beings: that we are imperfect idealists who frequently fall short of our ideals. This is the doctrine of Original Sin. There is nothing occult or mysterious about it and it is defined by St Paul in words of one syllable: “The thing I would not, that I do; and what I would, that I do not.” There is no better description of human nature than that.

The significant development in public morality which has taken place in our time is the profound shift in the understanding of our human nature. We no longer admit to being imperfect. We do not believe in Original Sin. We find such a concept offensive, demeaning, an insult to our much-vaunted “self-esteem” – a thing that has replaced “self-respect.” And what were once regarded as mortal sins are now only lifestyle choices.

How did this profound shift come about? It is implicit in the Enlightenment teaching about human perfectibility and all the airy waffle about Liberty, Equality and Fraternity. A warning: whenever you hear those slogans, the next sound you will hear is the mob and the rattle of the tumbrels.

But the greatest influence on our redefinition of human nature was the theory of evolution. Towards the end of the 19th century people, led by the likes of Herbert Spencer, came to imagine that just as the species was developing physically, so we are also developing morally. And so we invented the superstition which goes by the name “Progress.” It is this mindless belief in progress which leads commentators – John Humphrys only this morning – to be scandalised by the occurrence of something they regard as “medieval” or “primitive barbarity.” You hear often the anguished cry, “We don’t expect that sort of thing to happen in this day and age…in the 21st century…” etc. As if the mere passage of time bestowed upon us moral improvement. As if the 20th century had not surpassed all previous ages in the numbers slaughtered in wars and genocides.

These days, morality itself is merely what we find pleasant or agreeable. It is Benthamism: the notion that the only good is the maximisation of pleasure. As Nietzsche rightly said of it, “Pig philosophy.”